Central nervous system germinoma

22-year-old patient presented with a history of 1 month of symptoms characterised by headache accompanied by vomiting. The B-HCG in cerebrospinal fluid was 87.95 mIU/ml, carcinoembryonic antigen (CEA) and alpha-fetoprotein (Alpha-FP) were negative. The serum levels of B-HCG was 19.52 mIU/ml.

MRI shows a large pineal region mass with moderate enhancement with compression of the tectum resulting in obstructive hydrocephalus (Fig. 1, 2, 3).
On SWAN imaging the pineal calcification is confirmed to be placed centrally engulfing the pineal calcification (Fig. 4). On T2 the pineal mass is hyperintense (Fig. 5 ). Diffusion-weighted imaging (DWI) shows restriction with low apparent diffusion coefficient (ADC) values (Figure 6).

The masses of the pineal gland can be found incidentally in MRI in 1.4-10% of the cases, in autopsy the prevalence can increase up to 40%. The most frequent masses are cysts, followed by tumours and vascular lesions [1]. According to the World Health Organization (WHO), tumours can be divided into germ cell tumours and non-germinomatous tumours including teratomas, embryonal carcinoma, yolk sac tumours, choriocarcinoma, and mixed germ cell tumours [3]. The two most frequent are germinoma in 50-60% of cases and teratoma in 15% [1, 3].
The clinical manifestations can be diverse and result from direct compression on adjacent structures. The patient may complain of a headache or focal signs and symptoms [1, 2]. Direct compression on the aqueduct of Sylvius can cause obstructive hydrocephalus and symptoms of intracranial hypertension. When there is greater extension and compression on the mesencephalic tectum, it causes Parinaud syndrome, characterised by upward gaze palsy, light-near dissociation, and convergence-retraction nystagmus [1, 2, 3].
Germinomas have peak incidence between 10-19 years and are more frequent in men with a ratio of 5:1-22:1 [1, 3]. Germinomas are divided into two groups: germinomas and germinomas with syncytiotrophoblasts cells. Usually, B-HCG, and alpha-FP are not elevated. In some cases, B-HCG may be raised attributed to the presence of syncytiotrophoblasts [1, 2, 3]. The levels of B-HCG are higher in CSF than in serum [2].
Teratomas are the second place in frequency and are frequent in infancy or early adulthood. They are composed of at least two embryonic layers [1]. The alpha-FP and B-HCG can be positive in the cases of immature teratomas but not in mature teratomas [3].
Germinomas are soft tissue masses that enhance heterogeneously with the contrast, usually can promote calcification of the gland centrally [1]. In sequences in T1 and T2, they have an intensity similar to the cerebral parenchyma. There may be cystic component up to 52% [1, 3, 4]. In diffusion-weighted imaging (DWI) it shows restriction with low apparent diffusion coefficient (ADC) values [3, 4]. Intratumoral haemorrhage is a common finding [1, 3].
The prognosis is favourable. In cases of obstructive hydrocephalus, the ventricular drain accompanied by an endoscopic biopsy should be considered. Radiation is a curative option in most patients but may have unfavourable long-term effects. Chemotherapy can be used in patients with relapses [5].